1. Field of the Invention
This invention relates to a card-shaped data carrier comprising a card body with an antenna, and a chip module with an integrated circuit connected electrically with the antenna.
2. Related Art
Such a data carrier can be formed as a credit card, bank card, electronic purse, etc., and used for contactless completion of transactions, for example for paying a charge for short-distance passenger transport or paying a purchasing price for goods or services. Further, such a data carrier can be used as an identity card for noncontacting admission control. In this case an identification code is stored in the integrated circuit for enabling admittance to a closed-off area in a building.
DE 44 16 697 A1 discloses a number of variants for constructing and producing such a data carrier. It discloses inter alia a card body having a coil and a gap for receiving a chip module. The chip module is inserted into the gap in such a way as to form an electric connection between the integrated circuit of the chip module and the coil contained in the card body. No details are to be found in DE 44 16 697 A1 on the production of the gap and in particular the exposure of the coil terminals.
It is commonly known to produce a gap for mounting a chip module in a card body, for example with the aid of a suitable milling tool. With known techniques, however, no measures are provided to ensure that the terminals of an antenna integrated in the card body are exposed with sufficient precision and reliability. Contacting problems can therefore occur upon incorporation of the chip module.
The invention is based on the problem of forming a reliable electric connection in a card-shaped data carrier between a chip module and an antenna disposed in the card body.
The basic idea of the invention is to effect material removal on the terminals of the antenna when exposing said terminals as is necessary for contacting the antenna.
This procedure has the advantage that any layers of dirt or oxide present on the terminals are removed by the material removal, thereby creating optimum preconditions for a reliable electric connection between the terminals of the antenna and the integrated circuit of the chip module.
A further advantage of the invention is that a greater tolerance range is permissible for exposure of the antenna terminals if one includes material removal on the terminals, compared with exact exposure of the surface of the terminals. If the antenna terminals are localized very exactly in the card body, a tolerance in the order of magnitude of half the terminal thickness is readily permissible on the basis of the inventive method when exposing the antenna terminals.
In the preferred embodiment one effects the material removal necessary for exposing the antenna terminals by beveling the terminals. In this way one can considerably enlarge the permissible tolerance range since sufficient material for contacting the integrated circuit of the chip module is left with a bevel of the terminals over a relatively large feed area of the material-removing tool. This might at most shift the lateral place of contacting, which causes no great problems. A further advantage of the bevel is that a larger terminal area is available for contacting so that a reliable contact can be formed.
It is also especially advantageous to ascertain by means of a sensor signal when material removal on the antenna terminals begins. This sensor signal can be used for feed control of the material-removing tool, which can be controlled very exactly in this way, independently of the production-related dispersion of the position of the antenna terminals in the card body.